In general, tires are configured in such a manner as to include a plurality of tire rubber members and a plurality of reinforcement members which are mainly made up of cords. In a representative tire, as is shown in FIG. 7, respective portions such as an inner liner portion 51, a tread portion 52, side wall portions 53, rim strip portions 54 and the like are formed by rubber members which match properties required for the respective portions and these rubber members are combined with a carcass layer 55 which constitutes a cord-contained reinforcement member, a belt layer 56 and bead portions 57 to thereby make up a tire T2.
To build rubber members which make up the respective portions, rubber materials were extruded continuously to be built into rubber strips from an extruding machine via dies which match cross sectional shapes of the respective rubber members, and thereafter, the rubber strips so built were cut to constant dimensions to thereby obtain target rubber members. In building a tire, the rubber members were sequentially affixed together on a rotational support element such as a building drum.
In addition, in recent years, in order to reduce the rolling resistance of a tire, tread rubbers have been developed which use silica instead of carbon black as a strengthening agent. However, since the tread rubbers have an electric resistance which is higher than that of tread rubbers which is compounded with only carbon black, there has been caused a problem that static electricity conducted from a vehicle body or electricity generated by internal friction when rubber deforms is accumulated. Then, there have been proposed pneumatic tires with a static elimination function which are made up in parallel of a non-conductive rubber which contains silica or the like and a conductive rubber which is compounded with carbon black or the like so that electricity generated in the vehicle body is made to be discharged to the road surface from a tread surface thereof.
For example, there has been proposed a pneumatic tire with a static elimination function in which a tread portion is configured by winding sequentially both a non-conductive rubber strip member and a highly conductive rubber strip member along a circumferential direction of a tire in a spiral fashion in such a manner that the non-conductive rubber strip member and the highly conductive rubber strip member are disposed in an alternate fashion (for example, refer to Patent Document No. 1 below).
However, in the pneumatic tire, there is caused a fear that the non-conductive rubber strip material covers the highly conductive rubber strip material in the tread portion to thereby exhibit no static elimination function unless winding positions of the non-conductive rubber strip material and the highly conductive rubber strip material are adjusted with good accuracy. Moreover, in the event that the tread portion is formed such as a winding drum by a roller, the non-conductive rubber in the rubber strip material is pressed to expand to cover the conductive rubber during the pressing step, causing the fear that the static elimination function is not exhibited. In addition, at the time of processing a green tire under vulcanization, as with the aforesaid pressing step, the non-conductive rubber flows to cover the conductive rubber, leading to the fear that the static elimination function is not exhibited.    Patent Document No. 1: JP-A-2004-338621